1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to a Universal Plug and Play (UPnP) device, and more particularly, to a method and apparatus for managing information regarding a UPnP device when an Internet Protocol (IP) address of the UPnP device is changed.
2. Description of the Related Art
Since a personal computer (PC) can automatically recognize peripherals using a Plug and Play function, a user can easily install peripherals. UPnP is a technique of extending the Plug and Play function all over a network and allows devices (PCs, peripherals, home appliances, etc.) to automatically recognize each other when they are connected to the network.
FIG. 1 is a block diagram of a related art UPnP network system. Referring to FIG. 1, the related art UPnP network system includes a control point 11 and UPnP devices 12 and 13. In particular, the UPnP devices 12 and 13 may be a media server and a media renderer, respectively.
The control point 11 recognizes UPnP devices existing in a network and controls the recognized UPnP devices. The media server 12 provides UPnP content. The media renderer 13 renders the UPnP content provided by the media server 12 according to a UPnP standard. The media renderer 13 may be a digital TV reproducing media content.
FIG. 2 is a block diagram for illustrating transmission of a UPnP alive message in a related art UPnP network. When a device is added to the UPnP network, the device transmits a UPnP alive message in a format, shown in FIG. 2, to the control point 11. In detail, FIG. 2 illustrates a case where the media server 12 is added to the UPnP network.
FIG. 3 is a block diagram for illustrating transmission of a UPnP byebye message in a related art UPnP network system. When a device is removed from a UPnP network, the device transmits a UPnP byebye message in a format, shown in FIG. 3, to the control point 11. In detail, FIG. 3 illustrates a case where the media server 12 is removed from the UPnP network.
Meanwhile, since the UPnP network is based on a TCP/IP (Transmission Control Protocol/Internet Protocol), a UPnP device must have its own IP address. Thus, for the IP address, the UPnP device includes a DHCP (Dynamic Host Configuration Protocol) client module and an automatic IP module. When a DHCP server is not detected in a network in which the UPnP device is located, the automatic IP module generates an IP address and sets it as an IP address of the UPnP device. When a DHCP server is detected in the network in which the UPnP device is located, the DHCP client module requests the DHCP server to provide an IP address, obtains the IP address as per the request, and sets it as the IP address of the UPnP device.
However, sometimes an IP address of a UPnP device is changed while the UPnP device is connected to a UPnP network based on the IP address. For instance, when a lease period of an IP address of a UPnP device, which is prescribed by a DHCP server, expires, the DHCP server allocates another IP address to the UPnP device; or when the DHCP server does not normally operate, the automatic IP module generates another IP address.
When the IP address of the UPnP device is changed, a network connection based on the previous IP address is disconnected, and a network connection is established based on the new IP address. Therefore, the UPnP device transmits the byebye message illustrated in FIG. 3 to the control point 11 and then transmits an alive message, shown in FIG. 2, to the control point 11.
The change in the IP address of the UPnP device changes a uniform resource locator (URL) via which a control request, for example, a message requesting a Simple Object Access Protocol (SOAP), is transmitted to the UPnP device; and a URL via which a request for an event, for example, a message requesting a General Event Notification Architecture (GENA), is transmitted to the UPnP device. Also, information regarding the UPnP device based on the previous IP address, e.g., a state variable, is removed from the control point 11, and new information regarding the UPnP device is generated based on the new IP address.
In addition, if the IP address of the UPnP device is changed, all of the sessions based on the previous IP address are discontinued, thereby stopping a service irrespective of a user's wishes. Thus, the user must restart the stopped service. If the IP address of the media server 12 or the media renderer 13 is changed, the content streaming session based on the previous IP address is discontinued, and reproduction of content using the media renderer 13 is suddenly stopped. In this case, the user must detect a point where content streaming is discontinued and restart content streaming at the detected point based on a new IP address.